The main purpose of this study is to predict strong ground motions from future large earthquake for Karaj city, the capital of Alborz province of Iran. This city is an industrialized city having over one million populations and is located near several active faults. Finite fault modeling with a dynamic corner frequency has adopted here for simulation of future large earthquake. Target fault is North Tehran fault with the length of 110 km and rupture of west part of the fault which is closest to Karaj, assumed for this simulation. For seven rupture starting points, acceleration time series in the site of Karaj Caravansary -historical building- are predicted. Peak ground accelerations for those are vary from 423 cm/s2 to 584 cm/s2 which is in the range of 1990 Rudbar earthquake (Mw=7.3) . Results of acceleration simulations in different distances are also compared with attenuation relations for two types of soil. Our simulations show general agreement with one of the most well known world attenuation relations and also with one of the newest attenuation relation that hase developed for Iranian plateau.
For dynamic analysis of structures, selection of ground motion (GM) is a crucial problem. For design, a tough GM should be used. It is difficult, however, to find such GM, because different GM can be the toughest in terms of different aspect. Uncertainty of structural properties complicates the problem. In this paper, an approach is presented to select design GMs out of a set of possible GMs using feature indices which are related with expected damage mechanisms of the structure. Uncertainty of nonlinear response is also incorporated. Quality of the GM selected in this scheme depends on the index considered. This paper discusses the efficiency of various indices through numerical simulations. Results verify the performance of the presented method and clarify several conditions to be taken into consideration.